Management of copper pyrometallurgical slags: giving additional value to copper mining industry

543 Introduction During the last years, due to world-wide economic recession and a large inventory of stock, copper reached a historical value of 0.59 US$/pound in 2001. This fact meant closing down many important mining companies in the world, mainly in USA. On the other hand, strong environmental restrictions have been imposed on the mining activity, and it is expected they will become more rigorous in the future. Thus, companies have been forced to invest in new technologies regarding efficiency and clean processes. An approach to this new vision was presented in the last International Conference on Clean Technologies for the Mining Industry, held in Chile on May 20001. In most of the cases, investment in new technologies has contributed to cost reduction as well as to make companies more competitive. However, mining and metallurgical companies are facing serious financial challenges worldwide today, and at the same time they must survive with a wide range of new problems. Thus, mining companies have looked beyond technological innovation in order to improve their operations and, also, they are considering now the advantage of total mining resources, making profitable that which was considered wastes before2. In this regards, this project propose to obtain products with commercial value from slag, one of the more important waste generated during pyrometallurgical copper extraction. This waste contains interesting amounts of compounds with an important commercial value. The objective of this work is to identify the best-oriented process to obtain commercial products, considering slag as a new ‘mining resource’ with chemical and physical properties different from the original copper ores. The products or by-products to obtain are basically: copper, silica, iron oxides, precious metals and some others minor products reported by smelter plants. Currently, slags have been considered as material for road construction or abrasive material for cleaning metallic surfaces, amongst other uses3. However, this proposal is to search for specific products and for particular applications. For example, copper as copper sulphate solution could be transferred to a leaching plant to obtain copper electrochemically. Iron concentrate, depending on its chemical and physical characteristics, could be incorporated as part of pellets for iron production. Silica, in spite of its low price, could be re-used in the smelting plant as flux, and to fix iron oxides in slag. Precious metals such as gold and silver, ever in small quantities, have a market in the medium and/or small-size mining sector. Thus, rather than disposing of these slags, they can be used taking full advantage of their physico-mechanical properties and to recover some value contained in them. SÁNCHEZ, M., PARADA, F., PARRA, R., MARQUEZ, F., JARA, R., CARRASCO, J.C., and PALACIOS, J. Management of copper pyrometallurgical slags: giving additional value to copper mining industry. VII International Conference on Molten Slags Fluxes and Salts, The South African Institute of Mining and Metallurgy, 2004.